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vis: partial vis(3) port
This is a stopgap while I figure out how I should go about implementing vis(3). It's also important to have some vis(3) implementation so I can do integration tests on round-trips. Signed-off-by: Aleksa Sarai <asarai@suse.de>
This commit is contained in:
Aleksa Sarai
parent
cd1de45ba5
commit
44391840b6
2 changed files with 216 additions and 0 deletions
162
vis.go
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162
vis.go
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/*
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* govis: unicode aware vis(3) encoding implementation
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* Copyright (C) 2017 SUSE LLC.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package govis
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import (
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"fmt"
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"unicode"
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"unicode/utf8"
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)
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func isunsafe(ch rune) bool {
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return ch == '\b' || ch == '\007' || ch == '\r'
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}
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func isglob(ch rune) bool {
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return ch == '*' || ch == '?' || ch == '[' || ch == '#'
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}
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func ishttp(ch rune) bool {
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return unicode.IsDigit(ch) || unicode.IsLetter(ch) ||
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// Safe characters.
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ch == '$' || ch == '-' || ch == '_' || ch == '.' || ch == '+' ||
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// Extra characters.
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ch == '!' || ch == '*' || ch == '\'' || ch == '(' ||
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ch == ')' || ch == ','
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}
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func mapRuneBytes(ch rune, fn func(byte) string) string {
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bytes := make([]byte, utf8.RuneLen(ch))
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n := utf8.EncodeRune(bytes, ch)
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mapped := ""
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for i := 0; i < n; i++ {
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mapped += fn(bytes[i])
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}
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return mapped
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}
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// vis converts a single rune into its encoding, ensuring that it is "safe"
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// (for some definition of safe). Note that some visual characters (such as
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// accented characters or similar things) can be made up of several runes -- in
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// order to maintain my sanity Vis() makes no attempt to handle such cases
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// specially.
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func vis(ch rune, flag VisFlag) (string, error) {
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// XXX: Currently we are just allowing regular multi-byte characters such
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// as accents and so on to be passed through without encoding. Is this
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// really the best idea? In order to maintain compatibility with
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// vis(3) such that an older unvis(3) will do the right thing maybe we
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// should only output 7-bit ASCII? I'm not sure.
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if flag&VisHTTPStyle == VisHTTPStyle {
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// This is described in RFC 1808.
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if !ishttp(ch) {
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return mapRuneBytes(ch, func(b byte) string {
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return fmt.Sprintf("%.2X", b)
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}), nil
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}
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}
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// Handle all "ordinary" characters which don't need to be encoded.
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if !(flag&VisGlob == VisGlob && isglob(ch)) &&
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((unicode.IsGraphic(ch) && !unicode.IsSpace(ch)) ||
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(flag&VisSpace == 0 && ch == ' ') ||
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(flag&VisTab == 0 && ch == '\t') ||
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(flag&VisNewline == 0 && ch == '\n') ||
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(flag&VisSafe == VisSafe && isunsafe(ch))) {
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enc := string(ch)
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if ch == '\\' && flag&VisNoSlash == 0 {
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enc += "\\"
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}
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return enc, nil
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}
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if flag&VisCStyle == VisCStyle {
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switch ch {
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case '\n':
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return "\\n", nil
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case '\r':
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return "\\r", nil
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case '\b':
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return "\\b", nil
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case '\a':
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return "\\a", nil
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case '\v':
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return "\\v", nil
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case '\t':
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return "\\t", nil
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case '\f':
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return "\\f", nil
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case 0:
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// TODO: Handle isoctal properly.
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return "\\000", nil
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}
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}
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// TODO: ch & 0177 is not implemented...
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if flag&VisOctal == VisOctal || unicode.IsGraphic(ch) {
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return mapRuneBytes(ch, func(b byte) string {
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return fmt.Sprintf("\\%.3o", b)
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}), nil
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}
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return mapRuneBytes(ch, func(b byte) string {
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enc := ""
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if flag&VisNoSlash == 0 {
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enc += "\\"
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}
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// This logic is stolen from cvis, I don't understand any of it.
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if b&0200 != 0 {
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b &= 0177
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enc += "M"
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}
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if unicode.IsControl(rune(b)) {
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enc += "^"
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if b == 0177 {
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enc += "?"
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} else {
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enc += string(b + '@')
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}
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} else {
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enc += fmt.Sprintf("-%s", b)
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}
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return enc
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}), nil
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}
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// Vis encodes the provided string to a BSD-compatible encoding using BSD's
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// vis() flags. However, it will correctly handle multi-byte encoding (which is
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// not done properly by BSD's vis implementation).
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func Vis(src string, flag VisFlag) (string, error) {
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if !utf8.ValidString(src) {
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return "", fmt.Errorf("vis: input string is invalid utf8 literal")
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}
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output := ""
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for _, ch := range src {
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encodedCh, err := vis(ch, flag)
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if err != nil {
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return "", err
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}
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output += encodedCh
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}
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return output, nil
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}
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54
vis_test.go
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54
vis_test.go
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@ -0,0 +1,54 @@
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/*
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* govis: unicode aware vis(3) encoding implementation
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* Copyright (C) 2017 SUSE LLC.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package govis
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import (
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"testing"
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)
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func TestVisUnchanged(t *testing.T) {
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for _, test := range []string{
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"helloworld",
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"THIS_IS_A_TEST1234",
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"SomeEncodingsAreCool",
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"AC_Raíz_Certicámara_S.A..pem",
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} {
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enc, err := Vis(test, DefaultVisFlags)
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if err != nil {
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t.Errorf("unexpected error with %q: %s", test, err)
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}
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if enc != test {
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t.Errorf("expected encoding of %q to be unchanged, got %q", test, enc)
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}
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}
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}
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func TestVisChanged(t *testing.T) {
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for _, test := range []string{
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"hello world",
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"THIS\\IS_A_TEST1234",
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} {
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enc, err := Vis(test, DefaultVisFlags)
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if err != nil {
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t.Errorf("unexpected error with %q: %s", test, err)
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}
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if enc == test {
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t.Errorf("expected encoding of %q to be changed")
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}
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}
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}
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